A method of determining an azimuth and elevation of a radiation emission source using a single-axis direction finding system is provided. The method includes receiving a plurality of radiation signals at the single-axis direction finding system. The plurality of radiation signals are emitted from the radiation source, each of the plurality of radiation signals being received at one of a plurality of attitudes of the single-axis direction finding system. The method also includes measuring an angle of arrival of each of the plurality of radiation signals with respect to the single-axis direction finding system. Additionally, the method includes calculating an azimuth angle of each of the plurality of radiation signals with respect to the single-axis direction finding system using the respective measured angle of arrival. Further, the method includes calculating a respective vector corresponding to each of the azimuth angles at different elevation angles within a predetermined range. Further still, the method includes determining an elevation angle of the radiation emission source with respect to the single axis direction finding system by determining a conversion point of the vectors.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of determining an azimuth and elevation of a radiation emission source using a single-axis direction finding system, the method comprising the steps of: receiving a plurality of radiation signals at the single-axis direction finding system, the plurality of radiation signals being emitted from the radiation emission source, each of the plurality of radiation signals being received at one of a plurality of attitudes of the single-axis direction finding system; measuring an angle of arrival of each of the plurality of radiation signals with respect to the single-axis direction finding system; calculating an azimuth angle of each of the plurality of radiation signals with respect to the single-axis direction finding system using the respective measured angle of arrival; calculating a plurality of azimuth rate of change vectors using the calculated azimuth angle of each of the plurality of radiation signals; and determining an elevation angle of the radiation emission source with respect to the single-axis direction finding system by determining a convergence of the vectors.
2. The method of claim 1 wherein the step of receiving a plurality of radiation signals includes receiving a plurality of radiation signals at the single-axis direction finding system, the single-axis direction finding system being connected to an airborne platform.
3. The method of claim 1 additionally comprising the step of: at least partially correcting for a coning error in the calculated azimuth angle of the radiation emission source with respect to the single-axis direction finding system using the determined elevation angle of the radiation emission source with respect to the single-axis direction finding system.
4. The method of claim 1 wherein the step of receiving a plurality of radiation signals includes receiving at least three radiation signals at the single-axis direction finding system, the three radiation signals being emitted from the radiation source.
5. The method of claim 1 wherein the step of receiving a plurality of radiation signals includes receiving each of the plurality of radiation signals at at least one of a heading, roll, and pitch orientation of the single-axis direction finding system.
6. The method of claim 1 wherein the step of calculating an azimuth angle includes calculating an azimuth angle of each of the plurality of radiation signals with respect to the single-axis direction finding system using the respective measured angle of arrival, a respective attitude of the single-axis direction finding system, and an estimated elevation angle of the radiation emission source with respect to the single-axis direction finding system.
7. The method of claim 1 wherein the plurality of azimuth rate of change vectors are calculated using the relation A ij ( el ) A ( r i , p i , h i , el, i ) A ( r j , p j , h j , el, j ) /( t i t j ) , where el represents a range of elevation angles, i and j are two of the angle of arrival measurements, t i and t j are the times associated with the angle-of-arrival measurements, r i and r j are roll aircraft attitude values, p i and p j pitch aircraft attitude values, and h i and h j are heading aircraft attitude values.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 23, 2002
August 31, 2004
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